1. Technical Field
The present invention relates to an in-circuit test machine and, more particularly, to an in-circuit test machine testing circuit components soldered on a printed circuit board (PCB), further capable of testing connectors soldered on the printed circuit board and the soldering state of the connectors on the printed circuit board.
2. Related Art
Typically, when a large quantity of printed circuit boards are produced, an operator separates defective printed circuit boards from printed circuit boards that are not defective by manually bringing an in-circuit tester into contact with connecting terminals of respective circuit components soldered on the printed circuit board.
As a result of the manual intervention of the operator, a great amount of time is required for the test. And sometimes not all printed circuit boards are tested. Accordingly, a defective printed circuit board including defective circuit components may be included in products. When it is determined that a defective printed circuit board causes product defects in one of the final steps of a fabricating process, the product must be exploded and the defective printed circuit board must be replaced with a printed circuit board that is not defective. This results in a reduced fabricating efficiency, a waste of resources, and an increased cost.
Methods have been developed to automatically test circuit components on all printed circuit boards, as opposed to just some printed circuit boards. The testing occurs before the printed circuit boards are assembled as products. A printed circuit board to be tested is transferred to a predetermined position of a tester. A testing terminal of the tester is brought into contact with connecting terminals of respective components mounted on the printed circuit board to measure a testing value of a parameter. The testing value is compared with a reference value saved in a data storage unit of the tester. According to the result of the comparison, it is determined whether the is circuit components of the printed circuit board are defective or not.
However, a printed circuit board tester adapting such a method as described above cannot test connectors soldered on the printed circuit board. In general, a connector inputting and outputting power and data has two terminals. The first terminal is soldered on the printed circuit board. The second terminal is designed to receive another printed circuit board, a cable, a connector, or other device. The second terminal generally is not connected to anything at the time the printed circuit board is being tested. Accordingly, even though signals testing the connector are supplied through the first terminal (that is, the soldered terminal) of the connector by bringing a testing terminal of the tester into contact with the first terminal, the result signals are not outputted because the second terminal of the connector is not connected to anything and the connector is in an open circuit. Since the connector is in an open, it is impossible to determine whether the connector is defective or not defective.
Methods and devices have been developed to test printed circuit boards, connectors, and integrated circuits, as disclosed in U.S. Pat. No. 5,504,432 for system and method for detecting short, opens and connected pins on a printed circuit board using automatic test equipment issued to Chandler et al., U.S. Pat. No. 5,557,209 for identification of pin-open faults by capacitive coupling through the integrated circuit package issued to Crook et al., U.S. Pat. No. 5,621,741 for method and apparatus for testing terminal connections of semiconductor integrated circuits issued to Kohiyama, U.S. Pat. No. 5,656,646 for apparatus for testing printed circuit boards issued to Kit, and U.S. Pat. No. 5,689,191 for terminal in-connector checking device issued to Kashiyama.
Although presently there do exist methods and devices testing printed circuit boards, I have discovered that it would be desirable to improve an in-circuit test machine in order to test connectors and components of printed circuit boards more completely and efficiently.